JPH11143296A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent components of an image forming device from being adversely affected by the reverse rotation of a stepping motor by suppressing the occurrence of the reverse rotation of the stepping motor when it is stopped. SOLUTION: At the time of stopping the stepping motor, a CPU executes slow down control (a period A), so as to gently reduce speed and make a stop, without immediately outputting a stopping instruction signal, when the stepping motor is stopped from a normal rotation ω1 . Hunting at the time of stopping the stepping motor is reduced to decrease the number of the reverse rotations, by the above-mentioned control, so that the damage and degradation of the components such as a cleaning blade can be prevented in an electrophotographic recording system image forming device, for instance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus applied to a recording unit such as a facsimile apparatus, and more particularly to a control system for a stepping motor as a driving source in the image forming apparatus.

[0002]

2. Description of the Related Art A recording unit mounted on a facsimile apparatus mainly includes two types of a thermal recording system and an electrophotographic recording system.
There are two types of recording systems, and among them, the recording unit of the electrophotographic recording system has a structure in which a stepping motor is used as a main driving source of an image forming unit. The reason for this is that the stepping motor as a drive source has the advantage of being relatively easy to handle and of being low in cost among synchronous motors.

[0003] As a recording unit of the electrophotographic recording system,
Normally, the photoconductor is centered around a charging unit, a toner replenishing unit, a developing unit, a transfer unit, a static elimination unit, a cleaning unit, and the like.

Many of the cleaning units employ a cleaning means called a counter blade system in order to remove and recover the toner remaining on the photosensitive member. The specific structure of the cleaning means is that a cleaning blade made of plastic (for example, urethane rubber) is pressed against the surface of the photoreceptor with a certain amount of protrusion and pressing force to scrape off toner and the like remaining on the surface of the photoreceptor. It can be recovered.

[0005]

In the above-mentioned conventional recording unit, in which a stepping motor is used as a drive source, the stepping motor is driven by continuous vibration in principle. It is conceivable to enter a reverse rotation region with respect to the previous rotation direction. For example, as shown in the waveform diagram of time (t) -angular velocity (ω) at the output shaft of the stepping motor shown in FIG. 5, when the stepping motor is stopped immediately from ω ₁ at the time of steady rotation, the angular velocity is increased until the stopped state is stabilized. The state changes to the negative / negative region, and therefore, the user may enter the reverse region many times.

In the recording section of the electrophotographic recording system, when a stepping motor as a driving source enters a reverse rotation area, a photosensitive member which is set to be driven to rotate in a predetermined direction rotates reversely. The surrounding components may be adversely affected. For example, since the cleaning blade is in contact with the photoreceptor so as to be pressed against the photoreceptor, the contact portion of the cleaning blade is turned up by the reversal of the photoreceptor, and in an extreme case, the cleaning blade may be damaged. There is a problem that there is.

Accordingly, the present invention provides an image forming apparatus which solves the above-mentioned conventional problems, suppresses the occurrence of reverse rotation when the stepping motor is stopped, and can prevent adverse effects on components caused by the reverse rotation. The purpose is to:

[0008]

In order to achieve the above object, the present invention is directed to an image forming apparatus using a stepping motor as a main driving source of an image forming unit, wherein the stepping motor is gradually stopped when the stepping motor is stopped. It is equipped with a control unit that performs slow down control to decelerate and stop.With this configuration, the stepping motor gradually decreases the rotation speed and stops when stopped. Can be suppressed.

Further, according to the present invention, in the slowdown control process by the control unit, the influence of the deceleration load due to the inertial load at the time of stop can be reduced by accompanying the drive control at a low speed for a fixed time. Can be more effectively suppressed from occurring when the motor stops.

Further, according to the present invention, a stepping motor for performing a 1-2-phase excitation drive is used as the stepping motor, and when the stepping motor is stopped, a slowdown control for gradually decelerating and stopping the stepping motor is performed. This configuration includes a control unit that performs phase excitation drive control. With this configuration, in addition to the reverse rotation suppression effect by the slow down control similar to the above, the stepping motor is stopped by the two-phase excitation with a large static torque when stopping. Since hunting at the time of stopping can be suppressed, occurrence of reverse rotation at the time of stopping of the stepping motor can be more stably suppressed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic configuration diagram of an image forming unit in an image forming apparatus of an electrophotographic recording system for explaining an embodiment of the present invention. Reference numeral 1 denotes a drum type photosensitive member. , A charging roller 2, a cleaning blade 3, a transfer roller 4, a developing roller 5, and the like are provided.

In the image forming apparatus shown in FIG. 2, the photosensitive member 1 rotates counterclockwise, the surface of the photosensitive member 1 is uniformly charged by the charging roller 2, and the charged surface is optically written by the laser beam 6 based on image data. Is performed to form a latent image on the photoconductor 1. This latent image is developed with toner by the developing roller 5, and a toner visible image is formed.

A recording paper (transfer paper) P is conveyed to the nip portion between the photosensitive member 1 and the transfer roller 4 at a certain timing, and a toner visible image is transferred onto the recording paper P by the transfer roller 4 in the nip portion. Transcribed. Recording paper P after transfer
Is transported to an image fixing unit (not shown) to fix the visible toner image. Further, the surface of the photoreceptor 1 after the transfer moves to a position where the cleaning blade 3 is installed, and the residual toner and the like on the surface are scraped off and collected.

FIG. 1 is a block diagram showing the configuration of a drive control system according to this embodiment. Reference numeral 10 denotes a CPU (Central Processing Unit), 11 denotes a ROM which is a memory means for storing control program software, and 12 denotes a ROM. Is a generator for outputting a timing signal, 13 is a motor driver, 14
Denotes a stepping motor for driving the photoconductor 1 and the like in the image forming unit.

In the drive control system shown in FIG.
U10 refers to the drive sequence data held in the form of a data table from the ROM 11 and outputs the data to the generator 12. The generator 12 is mainly a CP
Based on the drive sequence data received from U10, a timing signal serving as an excitation control signal for each phase of the stepping motor 14 is generated, and the motor driver 13
Output to The motor driver 13 includes the generator 12
An excitation drive signal for each phase of the stepping motor 14 is generated based on the timing signal received from. Upon receiving a drive current based on the excitation drive signal, the stepping motor 14 rotates.

Next, control when the stepping motor is stopped, which is a feature of the first embodiment of the present invention, will be described.

That is, control data when the stepping motor 14 is stopped, such as a time-angular velocity control waveform diagram shown in FIG.
U10, when stopping the stepping motor 14 from the normal rotation omega _1, by referring to the control data, immediately without outputting a stop command signal, gradually slow down control for decelerating the carried lead to stop (period A ).

Such control makes it possible to reduce hunting when the stepping motor 14 is stopped. Therefore, as shown in the waveform diagram of time (t) -angular velocity (ω) on the output shaft of the stepping motor 14 shown in FIG.
_When stopped from _{1, the} angular velocity changes to the plus / minus region until it becomes stable in the stopped state, and the number of times that the vehicle enters the reverse rotation region and performs reverse rotation can be reduced.
As described in the related art, damage and deterioration of components such as the cleaning blade can be prevented.

FIG. 4 is a time-angular velocity control waveform diagram relating to stop control of the stepping motor according to the second embodiment of the present invention. Control data corresponding to this control waveform is stored in the ROM 11 or the like, and the CPU 10 when to stop the stepping motor 14 from the normal rotation omega _1,
With reference to the control data, a slowdown control is performed such that the deceleration is gently performed and a stop is performed without immediately outputting a stop command signal. In the second embodiment, the slowdown control is performed. 2 periods (A ₁ , A ₂ )
In the meantime, a low speed control period (B) with a constant low speed and a fixed period is set in the meantime.

According to such control, hunting at the time of stoppage can be further reduced as compared with the control of the first embodiment.

Next, a third embodiment of the present invention will be described. In the third embodiment, a stepping motor driven by 1-2 phase excitation is used as the stepping motor 14. Then, the stepping motor stop control in the first embodiment or the second embodiment is performed, and two-phase excitation driving with a large static torque is performed at the stop.

Specifically, as shown in the motor phase excitation sequence diagram shown in FIG. 7, drive control for stopping at status 1 or status 3 when stopping is performed. Statuses 1 and 3 have a static torque of 1.4 compared to statuses 2 and 4.
One time (theoretical value), the final hunting becomes smaller.

As an example of overall control, status 1
To start the excitation (driving), and control so that the number of excitations until the stop is an even number.

With such control, hunting at the time of stoppage can be further reduced as compared with the control of the first and second embodiments, so that the reverse rotation of the stepping motor at the time of stoppage is stably suppressed. It becomes possible.

[0026]

As described above, according to the image forming apparatus of the present invention, the rotation speed of the stepping motor can be gradually reduced when stopping, and the stepping motor can be stopped. And therefore,
Damage to components such as the cleaning blade caused by the reverse rotation of the stepping motor,
Deterioration can be prevented, and the quality of the formed image can be stabilized for a long time.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a drive control system according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an image forming unit in an electrophotographic recording type image forming apparatus for describing an embodiment of the present invention.

FIG. 3 is a control waveform diagram of time-angular velocity according to the stop control of the stepping motor according to the first embodiment of the present invention.

FIG. 4 is a control waveform diagram of time-angular velocity according to a stop control of a stepping motor according to a second embodiment of the present invention.

FIG. 5 is a waveform diagram of time-angular velocity on an output shaft of a stepping motor during stop control according to the related art.

FIG. 6 is a waveform diagram of time-angular velocity at the output shaft of the stepping motor during stop control according to the first embodiment of the present invention.

FIG. 7 is a motor phase excitation sequence diagram according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging roller 3 Cleaning blade 4 Transfer roller 5 Developing roller 6 Laser beam 10 CPU (Central processing unit) 11 ROM 12 Generator 13 Motor driver 14 Stepping motor

Claims (3)

[Claims] 1. An image forming apparatus using a stepping motor as a main drive source of an image forming unit, comprising: a control unit for performing a slowdown control for gradually decelerating and stopping when stopping the stepping motor. An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the slowdown control process performed by the control unit includes low-speed drive control for a predetermined time. 3. A stepping motor for performing a 1-2 phase excitation drive is used as the stepping motor, and when the stepping motor is stopped, a slow down control for gradually reducing and stopping the stepping motor is performed, and a two phase excitation drive is performed. 2. A control unit for performing control.
Or the image forming apparatus according to 2.